Ultrasonic degreaser



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XR 3,001,769 $3M TX w v #5 l/ Sept. 26, 1961 E. PLASSMEYER 3, ,76

ULTRASONIC DEGREASER Original Filed Jan. 4, 1956 2 Sheets-Sheet 1 2 m a t M a;

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Se t. 26, 1961 L. E. PLASSMEYER 3,

ULTRASONIC DEGREASER Original Filed Jan. 4, 1956 2 Sheets-Sheet 2 IN VEN TOR.

3,001,769 ULTRASONIC DEGREASER Louis Edward Plassmeyer, Evanston, 111., assignor to Phillips Manufacturing Company, Chicago, 11]., a corporation of Hlinois Continuation of application Ser. No. 557,267, Jan. 4, 1956. This application Feb. 27, 1959, Ser. No. 797,006 4 Claims. (Cl. 259-1) This application is a continuing application of my copending application Serial No. 557,267, filed on January 4, 1956, now abandoned, and is also copending with my application Serial No. 796,002, filed on February 27, 1959, for Ultrasonic Degreasing Apparatus.

This invention relates to an ultrasonic degreaser. An ultrasonic degreaser is a tank filled with a solvent such as trichloroethylene or perchlorethylene in which is submerged one or more transducers which convert electrical energy into supersonic vibrations in the solvent. These vibrations have the effect of impinging the molecules of the liquid against the surface of an article submerged therein with such force as to clean the surface far more effectively than is possible by dipping or brushing or either in combination with substantial heat. This method of cleaning was hailed two years ago as a great advance, but today it is languishing and that for one reason, the ultrasonic equipment is so expensive that the superior cleaning does not justify the additional capital invested excepting for a few applications.

The nature of the cost can best be understood by describing a typical supersonic degreasing installation. Referring to the drawings, FIGURE 1 is a sketch of a perspective view of a portion of a degreaser shown in a folder which advertises ultrasonic transducers. The unmeral 10 identifies a portion of a tank having a bottom 12 with side walls 14 and 16 which is filled with trior perchlorethylene 18. A conveyor track 20 is adapted to draw small carriages 22 longitudinally of the chamber and from each carriage is suspended an object to be cleaned 24. Mounted on each of the two side Walls 14 and 16 of the tank is an ultrasonic transducer assembly 26 and 28 and a third, 30', is positioned in the bottom. Each transducer assembly carries five transducers 32, 34, 36, 38 and 40, which are positioned in a straight line. Three ultrasonic assemblies are necessary because at high frequencies the vibrations are highly directional and the work itself has a shielding effect. At the higher frequencies, the ultrasonic assembly will clean on only that side of the work which is facing the transducers. 'At much lower frequencies, i.e., close to the audible range, the vibrations in the liquid are less directional and tend to wrap around the parts being cleaned.

Each of the ultrasonic assemblies shown in FIGURE 1 costs the manufacturer of a degreaser about $1,800.

In the illustration shown in FIGURE 1, the employment of three ultrasonic assemblies may be financially sound because of the large number of similar parts to be cleaned. However, the vast majority of degreasers in use are small tanks, having plan dimensions of two to three feet by four to six feet. Most are vapor degreasers, but many contain a liquid sump at one end in which an ultrasonic transducer assembly may be mounted. A popular degreaser offered by applicants employer has a plan area of about three and one-half feet by twenty inches with an eighteen-inch square liquid chamber at one end. This degreaser at present sells for under $1,000. In order to convert this equipment to ultrasonic degreasing, $5,400 worth of transducers would be required. Moreover, even the three assemblies shown in FIGURE 1 do not do a perfect job. The leading edge and the trailing edge in the direction of movement of the gear there shown 1s not Patented Sept. 26, 1961 done as well as the edges directly facing the transducers, and the top surfaces are definitely less well cleaned.

The principal object of this invention is to provide a degreaser utilizing just one ultrasonic transducer which, nevertheless, directs ultrasonic vibrations from more than one side wall of a liquid chamber toward a central point. The feature of this invention is the provision of a liquid sump for a degreaser having deflecting inside walls and holding elements for auxiliary deflecting plates which will reflect ultrasonic vibrations in selected directions.

Another object of this invention is to direct initially supersonic vibrations in the liquid along paths adjacent the side walls to a multiplicity of points from which the vibrations will be divided inwardly toward the work. A feature is the provision of deflecting plates positioned in the solvent so that supersonic vibration will be generated on both sides.

Another object of this invention is to provide an ultrasonic degreaser having a plurality of transducers, each having an outwardly directed ultrasonic vibration radiating surface, a separate reflector made of ultrasonically vibratable material positioned in the path of the band of ultrasonic vibrations produced by each individual transducer, and at least one reflector fixed to and spaced from the side wall of the sump wall, there being, as readily apparent, a gaseous medium, such as air, between the wall and the reflector.

Another object of this invention is to provide a simple means for changing the band of supersonic waves from vertical to horizontal or to any angle therebetween. By band, applicant refers to the parallel lines of supersonic vibrations that emanate from the row of five transducers shown in FIGURE 1. The theory of mounting these transducers in a line is that the transducers may be most effectively aimed at the work so that a maximum of direct vibrations will engage the work. Thus, if the work pieces in FIGURE 1 were elongated and moving through the solvent horizontally, then the ultrasonic transducer assemblies 26 and 28 would be turned on their sides so that the single work piece would receive the vibrations of all five transducers in passing through. Similarly, the transducer 30 would be turned degrees. This would make possible more rapid movement of the conveyor 20. If the work piece had a greater height than the diameter of the band of vibrations from a single transducer, then the practice would be to cant slightly the ultrasonic transducers 26 and 28 so that all parts of the work would come under the direct vibrations from at least one ultrasonic transducer assembly. Similarly, the angle of the ultrasonic assembly 30 would be changed to take care of a work piece whose Width exceeded the diameter of the band from one of the transducers.

It has heretofore been proposed to mount the ultrasonic transducer assembly outside the tank adjacent an opening. One of the features of the present invention is the provision of a means for mounting an ultrasonic transducer assembly on the outside of a tank so that the row of transducers may be changed easily from a horizontal position to a vertical position or to a selected diagonal position therebetween.

These and such other objects as may herelnafter appear are attained in the embodiments of the invention hereinafter described and disclosed in the accompanymg drawings, wherein:

FIGURE 1 is an illustration of an existing ultrasonic degreaser;

FIGURE 2 is a side elevation partly in section, and FIGURE 3 is a view taken on the line 5-3 of FIG- URE 2;

FIGURES 4 and 5 are bottom plan and side elevation views, respectively, partly in section of a square sump liquid degreaser for directing ultrasonic vibrations from a Zlurality of directions toward the center of the sump; an

FIGURE 6 is a view taken on the line 6-6 of FIG- URE 4 and omitting all interior deflectors and flanges for holding them.

Continuing to refer to the drawings. in FIGURE 2, the numeral 42 identifies a degreaser which is shown in longitudinal cross section. being a rectangular tank, the lower portion of which is divided into three sum s. a vaporizing sump 43. a distillate sump 44, and a liquid cleaning sump 6. The details of the construction of the degreaser with the exception of the liquid sump 46 are not important to this invention. The vaporizing sump has an opening 48 in the side wall through which may be inserted heating elements which may be of various kinds. The inside wall of the degreaser may be equipped with a trough 50 for carrying condensed solvent from the side walls to the liquid sump 46 or to a reservoir. If the degreaser is of the type that has a water jacket around the upper part of the degreaser, this will maintain the vapors in the degreaser below the top level. Otherwise, if the degreaser emplovs perchlorethylene, the vapor level will be maintained by a temperature control. These degreasers have safety controls on both the heating elements, where electric, and commonly are equipped with a pump, which supplies liquid solvent to a spray line.

Referring now to sump 46-, this sump is rectangular, the side walls being vertical excepting for wall 49 which may be called the vibration dispersion wall. This wall 49 is flat, being in a plane, and is canted slightly downwardly. Suspended from brackets such as 52 mounted on the inside of the wall of the chamber 46 opposite to the dispersion wall 49 is a housing containing the trans ducers of an ultrasonic assembly 54. The electric con nections are carried by conduit 56 outside of the chamber '46 to an electronic equipment and control box, not shown. The assembly 54 may be lifted out of the chamber 46. There are several of these transducer assemblies on the market and the exact nature of the source of the vibrations is not important insofar as this invention is concerned. The transducers must produce ultrasonic vibrations in a liquid. Preferably, for applicants degreaser, the vibrations are in the high frequency range and a suitable transducer should be employed. Mounted in a recess 58 of the housing 54 is a row of transducers 59, see also FIGURE 3. The center line 61 of these transducers is approximately in the same horizontal plane as the horizontal center line 60 of the diffusion wall 49.

Returning to FIGURE 2, the dash lines 62 indicate the path of the vibrations from the transducers 59 to the diffusion plate 49. The dot-dash lines 64 indicate the path of the reflected vibrations after striking the diffusion plate 49. The liquid level in the sump 46 is indicated at 66.

Let us suppose now that a gear 68 to be cleaned is being lowered into the sump. As it approaches the surface 65, it is bombarded by particles of liquid 70 expelled from the surface of the liquid by the vibrations in the liquid. This surface activity occurs even though the principal vibration lines are moving horizontally because there is a general diffusing from the transducers 59 just as light diffuses after passing through a hole. The result is that there is a cleaning action on the bottom of the gear as it descends into the liquid. When the gear reaches position 72, it is in the direct line of horizontal vibrations, although the sides near and away from the viewer do not get direct vibrations. As the gear moves into position 74, it commences to receive the downwardly deflected vibrations 64.

This simple arrangement has rendered unnecessary the employment of additional transducer assemblies. It is true that vibrating the diffusion wall 49 requires and therefore absorbs some energy and that the strength of the vibrations coming from that wall is substan i l y SS than those coming directly from the transducer 30. However, any deficiency can be cured by leaving the work in for a longer period of time. The degreaser shown in FIGURES 2 and 3 constitute applicants basic idea on supersonic degreasing.

The usable space in the chamber 46 may be enlarged by moving the transducer assembly 54 outside the sump, as illustrated in the second embodiment of the invention in FIGURES 4 through 6. Only that part of the degreaser is shown which corresponds with the sump 46 of the embodiment shown in FIGURE 2. Referring to FIG- URE 4, the side walls of the ultrasonic sump are designated by the numerals 84 and 86; the end wall, the numeral 88; the partition, the numeral 90; and the bottom, the numeral 92.

The end wall 88 has a circular opening 94, see also FIGURE 6, over the outside of which is mounted a cylin drical housing 96 in which is mounted the transducers. The housing 96 carries a ring flange 98 in liquid-tight engagement therewith. This ring flange has a plurality of bolt holes circumferentially equally spaced from each other by arc distances of 10 to 45, so that they may register with like spaced holes 97 drilled in the end wall 88, see FIGURE 6. By means of nuts and bolts, including a gasket 100, the housing 96 may be assembled in water-tight engagement with the periphery of the opening 94. Referring to FIGURE 6, the solid-line circles 110, 112, 114, 116 and 118, identify the transducer faces, which are in a straight line. It is apparent that the housing 96 can be mounted on the periphery of the opening 94 so that the transducers are in a vertical line 102, a horizontal line 104, or diagonal lines 106 and 108.

Referring to FIGURE 2, the transducers are shown horizontally, which means that the band of direct vibrations will be much wider than it will be high. This would be obtained by positioning the housing 96 of FIGURE 5, returning now to FIGURE 6, in the horizontal line 104. If a high but narrow band of ultrasonic vibrations were desired as provided in FIGURE 1 by the housing 26, the housing 96 of FIGURE 5, returning to FIGURE 6, would be rotated 90 so as to produce the vertical band. The advantage of this is that applicants degreaser may be adjusted for the particular shape of the work that has to be cleaned. The direct ultrasonic vibrations clean the fastest.

In FIGURES 4 and 5, applicant shows an ultrasonic sump having a plurality of sonic wave deflecting surfaces.

Positioned in front of the transducer 116 is a V-shaped deflector 126 which splits the gross quantity of these vibrations and directs them along the lines 128 and 130 toward corner deflectors 132 and 134, which in turn respectively direct the vibrations to the corner plates 136 and 138. These in turn direct the vibrations to the center point 198 to the sump 82.

The center transducer 114 is unobstructed. Dififusion plate 142 is positioned directly opposite transducer 114 and having a V-shaped cross section will throw the vibrations 144 inwardly and vibrations 146 upwardly.

The diflfusion plate 148 is identical with the plate 126, and similarly diffuses the vibrations from the transducer 112. The diffusion plate 149 is like diffusion plate 120, but is reversed and throws the vibrations upwardly to a plate 150 which directs them toward the center point 98 of the sump.

In the case of diffusion plates removably suspended entirely in the liquid such as 126, 120, 148, 149, there is not much loss of energy because while these plates reflect vibrations in the directions shown, they also transmit and generate vibrations through their opposite surfaces, so that they do not act like a shield as does the work itself. These plates are made of very light steel and vibrate in the liquid. The plates such as 122, 136 and 142, or any plate fixed to the side walls and not having liquid on both sides of its surface does absorb energy. Although energy is thereby absorbed, there is nevertheless attained maximum. efliciency with respect to the degreasing of the metal parts in reflecting the ultrasonic vibrations because of the presence of a gaseous medium such as air between the reflector and the respective side wall, there being a minimum of resistance to vibration of the reflector plates offered thereby.

From the description of the embodiment of the invention shown in FIGURES 4, 5 and 6, it is apparent that the principle of redirecting supersonic vibrations from a surface transducer which lies in a plane, may be modified to suit the inside configuration of any sump and more particularly by the use of removable diffusion plates such as 124 and 126, the ultrasonic vibrations may be directed toward a specific work piece" so as to obtain a maximum of efliciency where large numbers of one type of work piece are to be cleaned. Experimentation will also determine which reflectors should be submerged and which incorporated into side walls of the tank.

Having thus described applicant's invention, what he claims is:

1. A degreaser comprising a sump having a wall, a housing, a row of ultrasonic wave generating means mounted in said housing, each means having an ultrasonic radiating surface directed outwardly of the housing, an opening in the said wall of the sump capable of passing a direct band of ultrasonic waves moving at right angles to the radiating surfaces in any vertical, horizontal or intermediate position, and means for fastening the housing interchangeably in any of several selected positions on the outside of the opening and in liquid-tight connection therewith.

2. A degreaser comprising a sump having vertical side walls and a bottom, there being a circular opening in one side wall together with a plurality of equally spaced bolt holes around the circumference of said opening, a cylindrical housing having a recess in one end, a row of transducers mounted in said recess with their radiating surfaces lying in a common plane, an outwardly directed ring flange on the recess end of said cylindrical housing, there being like spaced holes around said flange for mating with the bolt holes around the opening in said wall of the sump, a gasket between the two sets of respective 6 holes, and nuts and bolts holding the cylindrical housing in assembled relationship with the side wall of the tank with the row of transducers in a vertical, horizontal or intermediate position depending upon the mating of the holes.

3. A degreaser comprising a sump having side walls and a bottom, a degreasing solvent in said sump, means for generating ultrasonic waves in communication with said sump, an ultrasonic vibration radiating surface lying in a plane on said means and directed inwardly of said sump, a train of reflectors having ultrasonic vibratable characteristics positioned within said sump and characterized by a first reflector of the train being in the path of the band of vibrations leaving the radiating surface at right angles thereto, and by the last reflector of the train being positioned to direct vibrations toward the center of the sump.

4. An ultrasonic degreaser comprising a chamber having a plurality of side walls, a degreasing solvent in said chamber, means for generating ultrasonic vibrations in and through said solvent, said means having at least one outwardly directed ultrasonic vibration radiating surface, a train of reflectors comprising at least one separate reflector made of ultrasonically vibratable material positioned in the path of a band of said ultrasonic vibrations, and at least one reflector made of ultrasonically vibratable material fixed to and spaced from one of said side walls, said latter reflector being separated from said side walls by a gaseous medium, said gaseous medium being enclosed by said reflector and said side walls, said reflector and said side walls separated by said gaseous medium being below the level of the solvent in said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,484,014 Peterson et al. Oct. 11, 1949 2,702,260 Massa Feb. 15, 1955 2,831,785 Kearney Apr. 22, 1958 2,855,526 Jones Oct. 7, 1958 2,864,592 Camp Dec. 16, 1958 2,888,939 Nitsche June 2, 1959 

